In the past, fluid fuels containing solid carbon particles have been made as a result of the availability of powdered coal. Coal mixed with a hydrocarbon fuel constitutes a combustible mixture having very satisfactory combustion properties. The addition of water to the mixture in amounts which do not exceed the amount of the main constituents has proved to contribute to the combustion efficiency of such a fuel, see, e.g., U.S. Pat. No. 1,431,225.
The use of such fuels appears imminent as a means of exploiting plentiful supplies of coal. However, a problem associated with such fuels relates to the requirement that they be stored in bulk for long periods, particularly in the case where such fuels are used for firing boilers in power stations or marine applications.
Accordingly, the invention has for its object the provision of a fuel product substantially composed of a liquid hydrocarbon fuel, finely divided coal particles suspended therein, and water, such a product being stable for a storage time of up to four months and longer.